As communication infrastructure is developed and then recent society is called to be ubiquitous society, a user can carry a terminal apparatus that is able to provide various services to the user through communication network at any time and at any place. However, if much more functions are provided to such a terminal apparatus carried by a user in order to take much more various services, it causes increasing a cost of the terminal apparatus. Furthermore, if a high capacity storage is provided to such a terminal apparatus, it causes problems about theft, lost and the like. In short, in the case that the user loses the terminal apparatus, it causes leaking secret information, such as personal information and confidential business information, stored on the lost terminal apparatus, and thus it cannot protect the secret information stored on the lost terminal apparatus.
Then, it becomes popular to utilize a thin client system. In the thin client system, such a terminal apparatus carried by a user is configured with minimum hardware, such as a memory, a network card and a graphic card. Actual main processing is performed on a server apparatus connected to the terminal apparatus through network. The terminal apparatus receives only results of the processing performed by the server apparatus, and displays information on the monitor based on the received results (Patent Application Laid-Open No. 2001-282747). Thus, it is possible to minimize the hardware required in the terminal apparatus, save cost and prevent further leaking information.
In addition, a thin client system with virtual personal computer (PC) technique has attracted attention for saving cost. The virtual PC technique is for virtualizing the hardware in the server apparatus with utilizing a virtual machine monitor technique (VMM technique), a hypervisor technique or the like, and then for operating plural guest OSs (virtual PC). Thus, it is possible to increase the number of terminal apparatuses that can simultaneously connect to the server apparatus.
[Patent Document 1] Patent Application Laid-Open No. 2001-282747